1. Observing the Solar System with HST Amy Simon NASA’s Goddard Space Flight Center

2. Observation Planning for Planets Location, location, location ◦ Planets move!  Need accurate ephemerides, tracking Timing ◦ Planets rotate  Need to track longitude, and satellites/shadows ◦ Planets change  Sudden, rapid response events Orientation ◦ Planets have varying obliquities, preferred axes for slits ◦ Problem for HST, will be worse for JWST Ideally, want to observe at opposition ◦ Used to be a problem for HST ◦ Will be a problem for JWST

3. Photometry Need accurate photometric calibration for many studies ◦ PHOTFLAM is used extensively to calculated the solar flux in each filter passband ◦ DN converted to “I/F” Filters/instrument performance should be monitored. WFPC2 CTE changes, etc.

4. Jupiter Spectrum May 2008

6. Cross calibration & time variability Hubble’s long life has led to studies of time variability ◦ Need accurate long-term calibration ◦ Need accurate cross-calibration WPFC2 focal planes ◦ PC vs WF3 show some mismatches WFPC2, ACS, WFC3 ◦ Some similar filters ◦ Even with different central wavelengths and pass bands, can get reasonably good agreement

7. WFPC2 PC only

8. WFPC2 PC & WF3

9. Long term trends in CTE, etc.

10. Oh, the games we play Normalized to 13° N

11. WFPC2 vs WFC3

12. Fringing and Vignetting Extended bright objects cause interesting effects in filters WFPC2 CH4 quad filters suffer from vignetting ◦ Can get saturation in the vignetted areas WFC3 long wavelength filters show fringing ◦ Correctable, with patience

13. WFPC2 CH4 quad vignetting

14. WFC3 Fringing

15. Lessons for the Future Most planetary observers don’t use IRAF! ◦ Helpful to have instrument throughput tables as text file – needed for calculating solar flux (even more helpful to have solar flux in each filter!) Keywords ◦ V3 PA not particularly helpful, but can be used with a planetary ephemeris to determine north angle ◦ PHOTFLAM – don’t change the units! ◦ CTE – helpful to have performance keywords Filter and performance monitoring Full frame bright object characterization ◦ Fringe flats Archive is actually set up reasonably well (though planet names are not NED resolvable!). ◦ New Planets Pipeline looks promising archive.stsci.edu/prepds/planetpipeline